Q: Car runs better if I unplug fuel injector 8 but makes a ticking noise and runs sluggish if it's connected 2006 Ford Mustang

Hello - your symptoms suggest a failing injector . It appears to be leaking when it’s plugged in, as well as noisy. Check for problem codes relating to a rich mixture,, although it’s possible that the oxygen sensors for that bank of cylinders is leaning out the other 3 on that side. This would create rough running for sure. That would explain the popping (probably backfiring or misfiring at least on the lean cylinders). I recommend a misfiring inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.